BioCryst antiviral shows promise treating Zika virus in mice

Shares of BioCryst Pharmaceuticals rose 15.5 percent Monday after the company reported that its experimental antiviral was successful in treating mice infected with the Zika virus.

The company will present results of its Zika treatment at a World Health Organization meeting this week in Geneva, Switzerland. The WHO has been at the forefront of monitoring the spread of the mosquito-borne Zika virus that is associated with severe birth defects in children.

BioCryst’s success in treating Zika-infected mice with its yet-unnamed drug, BCX4430, was the first good news for the company since its stock fell 71 percent in a single day after another drug failed to treat a hereditary swelling disorder in a clinical trial.

BioCryst shares closed Monday at $2.98, up 40 cents. The company’s stock is down 71 percent this year and well below its peak of $16.39 last year.

BCX4430 is being developed with federal funding to prevent epidemics and as a response to potential bioterror attacks. The drug has proven effective in treating monkeys infected with Ebola and Marburg viruses and is now being tested in humans.

In the mouse experiment, Utah State University researchers injected mice with BCX4430 at two dosage levels. At the higher dosage, seven of the eight infected mice survived 28 days. At the lower dosage level, none of the mice survived. None of the mice also survived that received a placebo or ribavirin, another antiviral.

In late 2014, BioCryst tcommercially developed its first drug, Rapivab, billed as the first new flu medication in 15 years. BioCryst’s licensing agreement for Rapivab gives the 69-employee company exclusive rights to U.S. stockpiling orders for biodefense and public health needs, although there is no expectation that an order is imminent.